import java.util.LinkedList;
import java.util.List;

public class Main {
     public class ListNode {
          int val;
          ListNode next;
          ListNode() {}
         ListNode(int val) { this.val = val; }
         ListNode(int val, ListNode next) { this.val = val; this.next = next; }
     }
     ListNode head = null;
    public static void main(String[] args) {
        List<Integer> list = new LinkedList<>();
        list.add(1);

    }
}